Feel slow on the uptake...
The Mummy’s Tomb follows The Mummy’s Hand, released 2 years prior. A recap of The Mummy's hand is narrated to a couple by an archaeologist in a classy living room. As the story goes, an archaeological site was desecrated and a mummy escaped. The undead mummy is spooky, but its legend feels incomplete compared to that of most monsters in the Universal collection.
The back and forth between past and present stories initially creates a convolution that makes the narrative unclear. This tale is not unlike Dracula’s. The big difference being that he who revives the mummy commands it while the vampire is independent. This is the clearest and more imaginative part of the movie. The rest is a mish-mash of empty character arcs and fluffy preliminary dialog.
This franchise could use substance and cohesion. Every installment of The Mummy takes two steps forward one step back when it comes to continuity. You can expect a little tension and scary visuals, though, in the midst of a confusing script. The film looks good, but it seems shot on a rush. The second half is more interesting than the first and the ending is cliched but satisfying.